Anything 1+ gallons would be great for them.. heater wise, look for an adjustable 25w heater, as it will fit in 1-4 gallons no problem.
Don't use desk lamps, as when you turn them off at night, the water will cool really fast and once more your fish is back in the cold. Going from warm to cold will cause health issues, lower his immunity, slower his metabolism and if too quickly, can cause shock. Never idea to warm with just a lamp.. has to be stable. You are on the right track for wanting a heater.
I purchase from here
comes within a week or less- I've used from the mini 25w to the 150w with no issues. The mini should fit in most tanks that are above a gallon, are adjustable (can't see the numbers, but you can watch the thermometer until you know where is the best setting - it goes pretty high, so you just need to barely turn it on for smaller tanks.
As for the live plants.. anubias tend to be good, can weigh it down by tieing it with either fishing line or sewing string to a rock or driftwood.. naja grass, java grass, java ferns.. those are just some low light - hardy plants. A moss ball doesn't actually take care of the algae problems, sadly.. it takes a bunch, etc, to do anything. But having a couple is still good as it is still live plants. Just you will have to rid any algae yourself is all.
Good luck, you are going to be a great owner :)